The Main Reason For 1-piece Threaded Ball Valve Leakage

1 Piece Threaded Ball Valve leakage primarily involves stuffing box leakage and closure member leakage.

The main causes of stuffing box leakage are:

① The packing is incompatible with the corrosiveness, temperature, and pressure of the working medium;

② Improper packing installation, especially spiraling the packing, is most likely to cause leakage;

③ The valve stem is not machined accurately or has a surface finish that is not smooth enough, or is elliptical or has nicks;

④ The valve stem has pitting or has rusted due to exposure to the elements;

⑤ The valve stem is bent;

⑥ The packing has aged due to excessive use;

⑦ Excessive abrasive operation.

The main causes of closure member leakage are:

① Improperly polished sealing surfaces;

② The seal ring is not tightly fitted to the valve seat and disc;

③ The disc is not securely connected to the valve stem;

④ The valve stem is bent, causing misalignment between the upper and lower closure members;

⑤ Closing too quickly, resulting in poor contact or damage to the sealing surfaces;

⑥ Improper material selection that cannot withstand the corrosive media;

⑦ Using a globe or gate valve as a regulating valve. The sealing surface cannot withstand the erosion of high-speed flowing media;⑧ Certain media gradually cool down after the valve is closed, causing fine cracks to appear on the sealing surface, which can also cause erosion;⑨ Some sealing surfaces are connected to the valve seat and valve disc with threads, which can easily produce oxygen concentration cells, corrode and loosen;⑩ Due to the embedding of impurities such as welding slag, rust, dust, or mechanical parts falling off in the production system and blocking the valve core, the valve cannot be closed tightly.